Polyurethanes are used in a variety of biomedical devices including artificial hearts, vascular grafts, catheters, and intra-aortic balloons. This proposal presents methods for the synthesis, characterization, and fabrication of polyurethaneurea (PUU) Primary Reference Materials (PRM). The proposed program involves the synthesis of a batch of additive-free PTMO based polyurethaneurea and a batch of additive-free PEO based polyurethaneurea followed by thorough characterization of the bulk and surface properties of cast films. Polymers that are free of unwanted surface active contaminants, as determined by ESCA and static SIMS, will be fabricated into film samples, 1 x 3 x 0.005 inches, and will be packaged, sterilized and characterized. Tubing extrusion methods will be evaluated for producing small diameter tubing samples with a 4 mm ID and 10 cm long. A feasibility study will be performed to determine if it is possible to fabricate implantable quality small diameter tubing 0.5 meter long. The effect of gamma radiation on physicochemical properties of polyurethaneureas will be determined. Changes in the surface properties of the PRM as a function of time/annealing will be assessed.